Melanin may promote photooxidation of linoleic acid

Randolph D. Glickman; Kwok-Wai Lam

doi:10.1117/12.209890

22 May 1995 Melanin may promote photooxidation of linoleic acid

Randolph D. Glickman, Kwok-Wai Lam

Proceedings Volume 2391, Laser-Tissue Interaction VI; (1995) https://doi.org/10.1117/12.209890
Event: Photonics West '95, 1995, San Jose, CA, United States

Abstract

We have previously shown that laser-exposed melanin granules isolated from the retinal pigment epithelium (RPE) are capable of oxidizing ascorbic acid. We are now characterizing the reactions of light- activated melanin with other cellular components such as linoleic acid, a polyunsaturated fatty acid. Commercial linoleic acid, and melanin granules isolated from bovine RPE cells, are mixed and exposed to the broad band output of a 150 W Xenon arc lamp or the CW output of an Argon laser. Native linoleic acid is separated from its hydroperoxides by HPLC, and the relative amounts of each are detected by UV absorbance at 210 and 232 nm, respectively. Exposure of the linoleic acid alone to the xenon arc source results in production of linoleic hydroperoxides (LHP) in an intensity-dependent reaction that doubles in extent over the temperature range of 0° to 80°C. Addition of melanin granules at a density of 10⁸ granules/ml reduces the production of LHP, probably because of light absorption and self-screening by the melanin. At or below a density of 10⁷ granules/ml, however, the light-driven production of LHP is enhanced, especially during exposure to the blue- green output of the Argon laser. Physiological antioxidants (Vit. C,E protect the linoleic acid from photo-oxidation in the presence or absence of melanin. These observations support the hypothesis that light-activated melanin can react with some cellular components and thereby contribute to photochemical damage, especially if endogenous antioxidants are depleted.

Citation Download Citation

Randolph D. Glickman and Kwok-Wai Lam "Melanin may promote photooxidation of linoleic acid", Proc. SPIE 2391, Laser-Tissue Interaction VI, (22 May 1995); https://doi.org/10.1117/12.209890

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available